1. Field
The present disclosure relates generally to power supplies, and, more specifically, the present disclosure relates to controllers for power supplies.
2. Background Information
Many electronic devices include a power supply to provide the device with a regulated direct current (DC) power source. One type of power supply that may be used to provide the regulated DC source is a switched mode power supply, which is popular due to its small size, good output regulation, high efficiency, and safety features. Switched mode power supplies may be used to convert an alternating current (AC) source or a high voltage DC source into a regulated DC source having a desired voltage. Based on the specific application, different types of switched mode power supplies with different control methods and different features may be used.
Typically, a switched mode power supply includes a switching element coupled to an energy transfer element. The energy transfer element provides galvanic isolation, preventing direct current from flowing between the input and the output of the power supply. Common examples of energy transfer elements include a transformer and coupled inductor, where electrical energy received by an input winding on the input side is stored as magnetic energy that may be converted back to electrical energy at the output side across an output winding.
Switched mode power supplies typically include a controller for causing the switching element to be switched between an ON state and an OFF state to regulate the amount of power transmitted across the energy transfer element and delivered to a load. The output of the energy transfer element may then be rectified and filtered to provide a regulated DC output.
Some switched mode power supplies include a controller for output regulation to maintain properties of the output between predefined threshold values. For instance, the controller may be implemented in an integrated circuit (IC) having multiple input and output terminals and configured to receive signals representative of the parameters of the switch mode power supply, process the sensed signals, and generate control signals to control the switching element to regulate the output of the power supply. For example, the controller may receive a feedback signal representative of the output of the power supply. Based on this signal, the controller may adjust the switching characteristics of the switching element to vary the amount of power transferred to the output of the energy transfer element, and thus, the output of the power supply.
Since the operation of the controller is based at least in part on the feedback signal, it is important that the feedback signal accurately reflects the output voltage. Errors in the feedback signal, for example, caused by a short, or unwanted coupling, between the feedback terminal of the controller and an adjacent terminal may result in improper output regulation, thereby causing the power supply to generate an output having an incorrect voltage.
Thus, circuitry for detecting unwanted couplings between terminals of a controller are desired.